Transcriptomic analysis of female and male gonads in juvenile snakeskin gourami (Trichopodus pectoralis)

The snakeskin gourami (Trichopodus pectoralis) exhibits sexual dimorphism, particularly in body size. Since the snakeskin gourami is usually marketed during sexual maturation, the sexual size dimorphism has become an economically important trait. Sex-biased gene expression plays a key role in phenotypic sexual dimorphism. Therefore, using high-throughput RNA sequencing (RNA-seq) technology, we aimed to explore the differentially expressed genes (DEGs) in ovary and testis during sex differentiation in juvenile snakeskin gourami. Our results revealed a number of DEGs were demonstrated to be overexpressed in ovary (11,625 unigenes) and testis (16,120 unigenes), and the top 10 female-biased (rdh7, dnajc25, ap1s3, zp4, polb, parp12, trim39, gucy2g, rtbs, and fdxr) and male-biased (vamp3, nbl1, dnah2, ccdc11, nr2e3, spats1, pih1d2, tekt3, fbxo36, and mybl2) DEGs were suggested to be mainly associated with ovary and testis differentiation, respectively. Additionally, using real-time reverse transcription polymerase chain reaction (qRT-PCR), validation of the differential expression of 21 genes that were previously shown to be related to gonad development was performed (ar, bHLH, cyp19a1, daz, dead-end, esrb, esrrg, gnrhr, gpa, gsg1l, hsd17B, mospd1, nanos-1, nanos-2, p53, piwi-1, piwi-2, rerg, rps6ka, tgf-beta, and VgR). The results showed a significantly positive correlation (0.84; P < 0.001) between the results of RNA-seq and qRT-PCR. Therefore, RNA-seq analysis in our study identified global genes that were associated with ovary and testis differentiation in the juvenile phase of the snakeskin gourami. Our findings provide valuable transcriptomic bioinformation for further investigation of reproductive biology and applications of sex manipulation.